different possible designs that will be simulated. Furthermore, autonomous

optimization seeks to reduce the time that an operator spends accessing simulation results by using statistical tools to evalu- ate data from many different designs at once. Autonomous optimization will comple- ment, and in some cases replace, the traditional methodology of manually setting up and simu- lating individual designs.

CONCLUSION By allowing the software to

Michigan; Tomas Mueller, Voxeljet USA, Canton, Michigan; Michael Lindberg, Ilmor Engi- neering Inc, Plymouth, Michigan

BACKGROUND 3D printing of cores and

From the Stevenson presentation on autonomous optimization, the macro-porosity prediction (a) for the best top riser design (transparent material is less than 1% porous). The micro-porosity prediction (b) for the best top riser design (transparent material is less than 0.5% porous).

make changes to CAD geom- etries and/or process parameters, the operator is relieved of time consuming and tedious work, while these tasks are completed in a more efficient manner. By considering more possible designs and evaluating the data for all designs in one common interface, the foundry en- gineer has a better chance of identifying important variables and of selecting a design that will perform more favorably in the face of common process variabil- ity and therefore reduce the likelihood of scrap and rework. Autonomous optimization was used

to evaluate 480 different designs from only three optimizations in the shared examples. By exploring large design spaces efficiently in a short period of time, multiple risering and gating designs developed in hours that are more robust than other approaches that may have taken days or weeks to produce using the tra- ditional method of setting up, simulating and assessing individual simulations. An autonomous design of experi- ment was used to compare five different possible gating approaches for the same casting. By using quantita- tive numerical outputs from autonomous optimization the foundry engineer is provided with an objective means of assessing the performance of each gating system. Discus- sion has been provided on

manufacturing considerations that the engineer must take into account when selecting the design to put into production.

By using autonomous optimization the engineer is given more options to choose from when weighing manufac- turing costs associated with imple- menting a given design against the predicted quality level of that design.

PRESENTATION Economic and Timing Benefits of

3D Printed Molds for Prototype and Production Castings

AUTHORS Oliver Johnson, Tooling and Equip-

ment International Corp., Livonia,

complete molds, without any requirement for tooling, is revo- lutionizing the industry of fast prototype casting manufacture. Tis new technology also offers distinct advantages for certain production castings. Te benefits of 3D printed

molds are illustrated by a direct comparison between this tech- nology and conventional soft

tooling manufacture for a complex thermal command center casting required to support early mechanical development testing. A small quan- tity of these A356-T6 castings were produced in 3D printed molds in less than three weeks. A comparison of the cost and timing of the two ap- proaches shows clear benefits for the 3D printing technology due to the complexity of the parts and the small quantity of parts required. Cost and timing is projected for larger quanti- ties to determine the cross-over point when tooling becomes the more cost effective technology. Additional examples incorporat- ing other part geometries illustrate the factors that influence this cross-over point; specific geometries are identified where 3D printing is advantageous even for se- ries production applications.


From the paper presented on 3D printed molds, this small but very complex pump housing will serve as an example of cross- over analysis for 3D printed sand versus conventional tooling.

For the thermal com- mand center where just two parts were required in a compressed timescale, clear advantages from both a cost and timing standpoint, to using 3D printed sand to manufacture the molds held clear advantages. If more than 21 parts were needed it would have become cost- effective to manufacture soft tooling, but 3D printing would still be advantageous

May 2016 MODERN CASTING | 55

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